The present invention relates generally as indicated to a cushioning conversion machine and method. More particularly, the present invention relates to a separator device, a constant-entry device, and/or a shaping member for use in a cushioning conversion machine or method.
In the process of shipping an item from one location to another, a protective packaging material is typically placed in the shipping case, or box, to fill any voids and/or to cushion the item during the shipping process. Some conventional commonly used protective packaging materials are plastic foam peanuts and plastic bubble pack. While these conventional plastic materials seem to adequately perform as cushioning products, they are not without disadvantages. Perhaps the most serious drawback of plastic bubble wrap and/or plastic foam peanuts is their effect on our environment. Quite simply, these plastic packaging materials are not biodegradable and thus they cannot avoid further multiplying our planet""s already critical waste disposal problems. The non-biodegradability of these packaging materials has become increasingly important in light of many industries adopting more progressive policies in terms of environmental responsibility.
These and other disadvantages of conventional plastic packaging materials has made paper protective packaging material a very popular alternative. Paper is biodegradable, recyclable and renewable; making it an environmentally responsible choice for conscientious industries. While paper in sheet form could possibly be used as a protective packaging material, it is usually preferable to convert the sheets of paper into a relatively low density pad-like cushioning dunnage product. This conversion may be accomplished by a cushioning conversion machine, such as that disclosed in U.S. Pat. No. 5,322,477. This patent is assigned to the assignee of the present application and its entire disclosure is hereby incorporated herein by reference.
The cushioning conversion machine disclosed in U.S. Pat. No. 5,322,477 comprises a conversion assembly which converts multi-ply stock material into a three-dimensional cushioning product and a stock supply assembly which supplies the multi-ply stock material to the conversion assembly. The conversion assembly includes the forming assembly which inwardly turns the lateral regions of the stock material as it travels downstream therethrough. This inward turning results the lateral regions of the stock experiencing edge tension which sometimes results in ripping or tearing of the stock material.
A need remains for further improvements to prevent excessive edge tension and/or the tearing associated therewith. This need is especially critical for the conversion of lesser quality and/or short fiber paper. Additionally or alternatively, a need remains for other improvements to the cushioning conversion machine to work in conjunction with tension-distributing devices or otherwise improve or enhance the conversion process.
The present invention provides a stock supply arrangement which prevents the stock material from abruptly experiencing inward turning just downstream of the stock supply assembly, or more particularly the separating device. The stock supply arrangement of the present invention allows a more gradual transition between the supply of the stock material to the conversion assembly and the inward turning of lateral regions of the stock material by the conversion assembly. Such a gradual transition is believed to reduce edge-tension in the stock material and/or otherwise enhance the conversion process.
More particularly, the present invention provides a cushioning conversion machine comprising a conversion assembly which converts a multi-ply stock material into a three dimensional cushioning product and a stock supply assembly which supplies the multi-ply stock material to the conversion assembly. The conversion assembly includes a forming assembly which inwardly turns lateral regions of the stock material as the stock material travels therethrough in a downstream direction. Preferably, the forming assembly comprises a chute and a shaping member positioned at least partially within the chute with the stock material passing through the chute and around the shaping member as it travels through the forming assembly.
According to one aspect of the invention, the stock supply assembly includes a stock-dispensing device which dispenses the multi-ply stock material from a continuous sheet or roll thereof and a separating device which separates the plies of the dispensed stock material upstream of the forming assembly. The separating device includes a plurality of transversely extending separating members which are positioned to engage respective plies of the multi-ply stock material. At least some of the separating members (and preferably all) are shaped to permit an initial inward turning of the lateral regions of the stock material in the same direction as the forming assembly. In this manner, there is a more gradual transition between the supply of the stock material to the machine""s conversion assembly and the inward turning of lateral regions by the conversion assembly.
The preferred separating members are shaped such that tension is substantially evenly distributed throughout the full width of the stock material. At least some (and preferably all) of the separating members have a bowed or curved configuration and thus do not follow a transverse linear path perpendicular to the upstream-downstream direction. The direction of concavity of the bowed separating members corresponds to the direction which the lateral regions of the stock material are inwardly turned. The magnitude of concavity of the bowed separating members is such that there will be a gradual transition between the curvature of the stock material from the separating device to the forming assembly.
In the preferred cushioning conversion machine, the stock supply assembly is adapted to supply stock material which is between 25 to 35 inches wide and more preferably between 27 and 30 inches wide. The conversion assembly converts this stock material into a cushioning product which is approximately 8 to 9 inches wide. With such a cushioning conversion machine, the radii of curvature of the bowed separating members is preferably between 26 and 34 inches, more preferably between 27 and 33 inches, and even more preferably between 28 and 32 inches. The radii of curvature preferably varies between the bowed separating members, and preferably increases from the separating member which engages the ply of stock material which forms the inner ply in the cushioning product to the separating member which engages the ply of stock material which forms the outer ply in the cushioning product. Additionally, the radii of curvature of the separating members are preferably concentric to create a xe2x80x9cbull""s eyexe2x80x9d arrangement.
According to another aspect of the invention, the stock supply assembly includes a constant-entry device which also functions temporarily as a force dampening device during a high tension situation, such as during a start-up situation when it is necessary to overcome the starting momentum of the stock roll. The constant-entry device automatically returns to its normal operating position once the high-tension situation is relieved. When the stock material passing over the constant entry device is subjected to high tension, a guide roller of the constant entry device moves against a biasing force to limit the tension on the paper. During such yielding movement of the guide roller, the entry point is shifted in a range that is great enough to provide sufficient tension relief while at the same time being limited enough to insure adequate conversion of the stock material. Preferably the range of permitted movement is between 2xc2xd inches and 4xc2xd inches and is accomplished by the spring-loading of the guide roller which engages the stock material.
According to another aspect of the invention, the shaping member of the forming assembly has portions which define a turning perimeter around which the lateral regions of the sheet-like stock material are inwardly turned and portions which define a holding surface that holds the central regions of the stock material as its lateral regions are inwardly turned. The turning perimeter includes co-planar portions and at least one protrusion which projects beyond these co-planar portions. The protrusion is preferably positioned adjacent the downstream end of the shaping member and within the chute. Additionally or alternatively, the holding surface includes at least one protrusion which projects beyond a plane extending from the downstream edge of the holding surface to the upstream edge of the holding surface.
According to a further aspect of the invention, a separating device includes a plurality of transversely extending separating members which are positioned to engage respective plies of the mutli-ply stock material, at least one of which has end portions and a central portion therebetween. The end portions are inwardly tapered relative to the central portion towards the respective ends of the member and are positioned to engage the ends of the lateral portions of at least one of the plies of stock material. Preferably, at least two the transversely extending members of the separating device have inwardly tapered lateral end portions. More preferably an outer transversely extending member (positioned to engage an outer ply of the multi-ply stock material) and an inner transversely extending member (positioned to engage an inner ply of the multi-ply stock material) both have inwardly tapered lateral end portions. Also preferably, an intermediate transversely extending member (positioned to engage an intermediate ply of the multi-ply stock material) does not include inwardly tapered lateral end portions.
The separating members including the inwardly tapered lateral end portions preferably comprise a non-rotatable rod and a sleeve. The sleeve is rotatably mounted around the rod and defines at least the central portion of the separating member. In one embodiment of the invention, the sleeve defines only the central portion and the separating member includes end caps which define the inwardly tapering end portions. In another embodiment of the invention, the sleeve defines both the central portion and the inwardly tapering end portions of the separating member.
In the preferred embodiment, the transversely extending member having the inwardly tapered end portions is incorporated into the machine""s separating device. However, the incorporation of such a member into a cushioning conversion machine which does not include a separating device is possible with, and contemplated by, the present invention. The stock supply assembly of such a machine would include a stock-dispensing device which dispenses the multi-ply stock material from a continuous sheet thereof and the transversely extending member would be positioned to engage at least one of the plies of the dispensed mutli-ply stock material.
The present invention also provides a cushioning conversion method comprising the steps of supplying a multi-ply stock material and converting the stock material into a three dimensional cushioning product. The converting step includes inwardly turning lateral portions of the stock material as the stock material travels in a downstream direction. The supplying step includes dispensing the stock material from a continuous sheet of multi-ply stock material and engaging at least one ply of the dispensed stock material with a transversely extending member which allows inward urging of the lateral end portions of the at least one ply in the same direction as the inwardly turning step of the converting step. Preferably, the supplying step also includes the step of separating the plies of stock material and the engaging step is performed at the same time as said separating step.
The foregoing and other features of the invention are hereinafter fully described and particularly pointed out in the claims. The following description and annexed drawings setting forth in detail a certain illustrative embodiment of the invention, this being indicative, however, of but a few of the various ways in which the principles of the invention may be employed.